Positional sensing : piezo wiring

[drumdhiver]

I all !

I find in my documents this picture which was joint with cone foam...
we can see that rim piezo's wiring is inverted between ring n' ground.
We can read it on Megadrum miscelaneous settings, about Positional sensing :

"he first half wave of a signal from a pad should be positive, e.g my Pintech mesh snare is such a pad. Most of other mesh pads out there, like Roland, Drumtec and etc, produce a negative first half wave. In this case you will have to use a full wave precision rectifier. See viewtopic.php?f=3&t=1215 for details."

Dimitri, did you talk about inverted wiring on head piezo?



I'm not able to have correct variation for positional sensing... Is head piezo must be place on rigid or smooth surface for bests results?


I buid my own drums like these draws






See you !

[dmitri]

Are you using a precision rectifier on the input? Without it, it may work or it may not. My Pintech 10" snare works without the precision rectifier but when I had them for testing, neither with Drumtec 14" nor with Roland PD-125X Positional sensing did not work properly without the precision rectifier on the input. Reversing piezo polarity may help but I made this suggestion based on the fact that my Pintech 10" snare produces positive first half waves.

[drumdhiver]

Hi!

How can I use precision rectifier? is it included in the positional sensing board?

Is the inversion polarity for rim piezo should modify head sensor?

[dmitri]

Hi!

How can I use precision rectifier? is it included in the positional sensing board?

Positional sensing board includes 5 precision rectifiers.

Is the inversion polarity for rim piezo should modify head sensor?

In what way?

[drumdhiver]

Snare is plug on snare input, I set Position level on 3, Low/High values are 1 & 7... I don't really which values I have to set.

How can I use precision rectifiers???

for polarity on piezo, I asked this question compared with this schematic :
(you can see on rim piezo inversion between +/- sleeve/ring


http://www.hostingpics.net/viewer.php?i ... img023.jpg

[dmitri]

Snare is plug on snare input, I set Position level on 3, Low/High values are 1 & 7... I don't really which values I have to set.

How can I use precision rectifiers???

Do you have the Positional sensing addon or not?

for polarity on piezo, I asked this question compared with this schematic :
(you can see on rim piezo inversion between +/- sleeve/ring


http://www.hostingpics.net/viewer.php?i ... img023.jpg

I don't get the question. Is it about reversing polarity on the head piezo? With the Positional sensing addon it doesn't matter.

[dmitri]

According to viewtopic.php?f=3&t=2631 you do have the Positional sensing addon board.
In this case see viewtopic.php?f=3&t=2052 for how I configured positional sensing with Drumtec 14" and Pintech 10".
Also read about PositionalLv in http://www.megadrum.info/content/miscellaneous-settings
Please, note that I've never used DIY mesh type snares so cannot advise you on best design apart from the requirement that the head piezo must be centrally located.

[drumdhiver]

" According to viewtopic.php?f=3&t=2631 you do have the Positional sensing addon board. " Exact !

Hello Dimitri,

I modify head piezo support by removing foam : the piezo is attached directly on rigid structure, it work better !

I observed that, when I hit the head softly, CC16 variation (there's a vertical bar indicator on BFD3) seems to correspond to the different zones. If I hit harder, the detection of side/center is false, I may probably need to install voltage divider, like you advised.

I will try it.

[ignotus]

Try tightening the drum head and raising minscan, it might help.

[dmitri]

On the inputs with precision rectifiers you don't need voltage dividers.
Positional sensing quality depends heavily on the pad itself - design, mesh head, and, as ignotus advised, on head tension.